Line connection devices for connecting at least two media lines or sub-media lines or one media line with a unit as well as multipart heatable media lines comprising such line connection devices and (sub-)media lines are known in the prior art. The media line can be pipe or hose lines. On the one hand the line connection device can serve to connect sub-media lines or media lines and on the other hand to connect a media line with a unit or connection device of a unit. At the connection ends all these components are connected to the line connection device. The connection ends can therefore be designed in various forms, e.g. as coupling portions for receiving plug components, as connection sections that can connected to the media lines in a bonded manner, as mandrel sections for flare fitting, in particular of hose lines etc.
Multipart heatable media lines for conducting fluid media are used in particular in vehicles, wherein the line connection devices are used for the coupling or interconnection of several heatable sub-media lines to the multipart heatable media lines. For transporting medium within the line connection device, provided therein is an inner medium channel or a channel-like through opening which extends between the connection ends and has a sufficiently dimensioned inner diameter or adequate clearance for medium to be conveyed through. In the interior of the line connection device the medium channel therefore forms a fluid or flow connection of the at least two connection ends thereof.
At low temperatures the medium flowing through the media lines or sub-media lines is at risk of freezing, for which reason it is also known to heat these lines and the line connection device connecting them. Media are often conducted through the multipart heatable media line which due to a relative high freezing point often tend to freeze at still quite high ambient temperatures, as a result of which the functioning, of a vehicle for instance, is impaired or even seriously disrupted. This is clearly the case in connection with media lines conveying water as well as media lines through which an aqueous urea solution flows as medium, used as an NO reaction additive with so-called SCR catalysts (SCR=Selective Catalytic Reduction). Therefore a possibility or heating the media line, or at least parts thereof and the line connection device, is envisaged in order prevent freezing of the medium within the multipart heatable media line or to allow thawing of an already frozen medium. Additionally, for the external thermal insulation and also for protection against damage, it is also known to provide multipart heatable media lines, including the line connection device and various transition areas between these with at least one insulation device or encapsulation. Devices for heating a line connection device and also an outer encapsulation are known from EP 1 985 908 B1 for example.
In order to monitor and control the properties of the medium flowing through the media lines or multipart heatable media lines, particularly during the operation of the vehicle, but also while it is at a standstill, it is also known to provide measuring devices in the region of line connection devices which connect several sub-media lines to form one multipart media line. Such measuring devices can be permanently integrated herein, as disclosed, for example, in DE 10 2009 060 363 A1, or arranged as plug-type connections in a corresponding coupling portion in the line connection device, as disclosed in WO 2013/130810 A1. According to this prior art document a sensor holder is provided in an SCR system which comprises a pipe, a chamber and a retaining device. The pipe has an inlet for receiving fluid flowing in from a first SCR line and an outlet for conducting outflowing fluid to a second SCR line. The pipe also has a through opening extending between the inlet and the outlet. The chamber has an interior which is accessible from the through opening for receiving an SCR sensor, and an opening leading to the interior. The retaining device has a section which can be moved into the chamber opening. On moving the section in the opening in the direction of the interior the section comes into contact with the SCR sensor and holds the sensor firmly in the holder. On moving the section away from the interior it is possible to release the SCR sensor from the holder. It is also disclosed that at least one resistor wire can be arranged around at least one section of the pipe and the media line in order to emit heat into the pipe.
For sealing off the electronic component of the sensor or the sensor element itself from the medium flowing through the pipe, the SCR system according to WO 2013/130810 A1 requires seals. If the medium freezes within the pipe provided with the sensor, the pipe can be damaged by the forming ice. In particular, through the frozen medium, which takes up a greater volume compared with the fluid medium, the sensor could be pushed out of its sensor holder or at least be jammed into its position and possibly be damaged thereby. Additionally, due to the displacement, possibly also of the seals, leakage cannot be avoided on thawing out.